HBASE-30169 Split completed parent region added to RIT list on host RS and master crash

hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/AssignmentManager.java

@@ -1892,9 +1892,10 @@ public void visitRegionState(Result result, final RegionInfo regionInfo, final S
       }
       // add regions to RIT while visiting the meta
       regionInTransitionTracker.handleRegionStateNodeOperation(regionNode);
-      // If region location of region belongs to a dead server mark the region crashed
+      // If region is supposed to be serve traffic (NOT split and merged) and location of region
+      // belongs to a dead server mark the region crashed
       if (
-        regionNode.getRegionLocation() != null
+        regionNode.getRegionLocation() != null && !AssignmentManagerUtil.isSplitOrMerged(regionNode)
           && master.getServerManager().isServerDead(regionNode.getRegionLocation())
       ) {
         long timeOfCrash = master.getServerManager().getDeadServers()
@@ -2116,10 +2117,6 @@ public List<RegionStateNode> getRegionsInTransition() {
     return regionInTransitionTracker.getRegionsInTransition();
   }
 
-  public boolean isRegionInTransition(final RegionInfo regionInfo) {
-    return regionInTransitionTracker.isRegionInTransition(regionInfo);
-  }
-
   public int getRegionTransitScheduledCount() {
     return regionStates.getRegionTransitScheduledCount();
   }

hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/AssignmentManagerUtil.java

@@ -35,6 +35,7 @@
 import org.apache.hadoop.hbase.client.RegionInfo;
 import org.apache.hadoop.hbase.client.RegionReplicaUtil;
 import org.apache.hadoop.hbase.favored.FavoredNodesManager;
+import org.apache.hadoop.hbase.master.RegionState;
 import org.apache.hadoop.hbase.master.procedure.MasterProcedureEnv;
 import org.apache.hadoop.hbase.util.FutureUtils;
 import org.apache.hadoop.hbase.wal.WALSplitUtil;
@@ -298,4 +299,16 @@ static void checkClosedRegion(MasterProcedureEnv env, RegionInfo regionInfo) thr
         + ", abort split/merge to prevent data loss");
     }
   }
+
+  /**
+   * For splitting, need to test both region info and state, and will return true if either of the
+   * test returns true. Please see the comments in
+   * {@link AssignmentManager#markRegionAsSplit(RegionInfo, ServerName, RegionInfo, RegionInfo)} for
+   * more details on why we need to test two conditions.
+   */
+  static boolean isSplitOrMerged(RegionStateNode regionStateNode) {
+    return regionStateNode.getState() == RegionState.State.SPLIT
+      || regionStateNode.getRegionInfo().isSplit()
+      || regionStateNode.getState() == RegionState.State.MERGED;
+  }
 }

hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/RegionInTransitionTracker.java

@@ -41,22 +41,22 @@ public class RegionInTransitionTracker {
 
   private final List<RegionState.State> ENABLE_TABLE_REGION_STATE = List.of(RegionState.State.OPEN);
 
+  // DO NOT USE containsKey()/remove() on regionInTransition with a different RegionInfo instance:
+  // this map is ordered by RegionInfo.COMPARATOR, and that comparator includes the offline flag.
+  // Lookups can therefore fail if the RegionInfo used as the key has a different offline value,
+  // even when it refers to the same region. Offline value changes with splitting.
   private final ConcurrentSkipListMap<RegionInfo, RegionStateNode> regionInTransition =
     new ConcurrentSkipListMap<>(RegionInfo.COMPARATOR);
 
   private TableStateManager tableStateManager;
 
-  public boolean isRegionInTransition(final RegionInfo regionInfo) {
-    return regionInTransition.containsKey(regionInfo);
-  }
-
   /**
    * Handles a region whose hosting RegionServer has crashed. When a RegionServer fails, all regions
    * it was hosting are automatically added to the RIT list since they need to be reassigned to
    * other servers.
    */
   public void regionCrashed(RegionStateNode regionStateNode) {
-    if (regionStateNode.getRegionInfo().getReplicaId() != RegionInfo.DEFAULT_REPLICA_ID) {
+    if (isReplica(regionStateNode)) {
       return;
     }
 
@@ -76,7 +76,7 @@ public void regionCrashed(RegionStateNode regionStateNode) {
    */
   public void handleRegionStateNodeOperation(RegionStateNode regionStateNode) {
     // only consider default replica for availability
-    if (regionStateNode.getRegionInfo().getReplicaId() != RegionInfo.DEFAULT_REPLICA_ID) {
+    if (isReplica(regionStateNode)) {
       return;
     }
 
@@ -86,10 +86,7 @@ public void handleRegionStateNodeOperation(RegionStateNode regionStateNode) {
       tableEnabled ? ENABLE_TABLE_REGION_STATE : DISABLE_TABLE_REGION_STATE;
 
     // if region is merged or split it should not be in RIT list
-    if (
-      currentState == RegionState.State.SPLIT || currentState == RegionState.State.MERGED
-        || regionStateNode.getRegionInfo().isSplit()
-    ) {
+    if (AssignmentManagerUtil.isSplitOrMerged(regionStateNode)) {
       if (removeRegionInTransition(regionStateNode.getRegionInfo())) {
         LOG.debug("Removed {} from RIT list as it is split or merged",
           regionStateNode.getRegionInfo().getEncodedName());
@@ -153,4 +150,9 @@ public List<RegionStateNode> getRegionsInTransition() {
   public void setTableStateManager(TableStateManager tableStateManager) {
     this.tableStateManager = tableStateManager;
   }
+
+  private static boolean isReplica(RegionStateNode regionStateNode) {
+    return regionStateNode.getRegionInfo().getReplicaId() != RegionInfo.DEFAULT_REPLICA_ID;
+  }
+
 }

hbase-server/src/test/java/org/apache/hadoop/hbase/master/assignment/AssignmentTestingUtil.java

@@ -49,12 +49,17 @@ private AssignmentTestingUtil() {
   }
 
   public static void waitForRegionToBeInTransition(final HBaseTestingUtil util,
-    final RegionInfo hri) throws Exception {
-    while (!getMaster(util).getAssignmentManager().isRegionInTransition(hri)) {
+    final RegionInfo hri) {
+    while (!isRegionInTransition(hri, getMaster(util).getAssignmentManager())) {
       Threads.sleep(10);
     }
   }
 
+  public static boolean isRegionInTransition(RegionInfo hri, AssignmentManager am) {
+    return am.getRegionsInTransition().stream()
+      .anyMatch(rsn -> rsn.getRegionInfo().getEncodedName().equals(hri.getEncodedName()));
+  }
+
   public static void waitForRsToBeDead(final HBaseTestingUtil util, final ServerName serverName)
     throws Exception {
     util.waitFor(60000, new ExplainingPredicate<Exception>() {

hbase-server/src/test/java/org/apache/hadoop/hbase/master/assignment/TestRegionSplit.java

@@ -19,6 +19,7 @@
 
 import static org.apache.hadoop.hbase.master.assignment.AssignmentTestingUtil.insertData;
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
@@ -117,8 +118,8 @@ public void testSplitTableRegion() throws Exception {
     int splitRowNum = startRowNum + rowCount / 2;
     byte[] splitKey = Bytes.toBytes("" + splitRowNum);
 
-    assertTrue(regions != null, "not able to find a splittable region");
-    assertTrue(regions.length == 1, "not able to find a splittable region");
+    assertNotNull(regions, "not able to find a splittable region");
+    assertEquals(1, regions.length, "not able to find a splittable region");
 
     // Split region of the table
     long procId = procExec.submitProcedure(
@@ -127,7 +128,7 @@ public void testSplitTableRegion() throws Exception {
     ProcedureTestingUtility.waitProcedure(procExec, procId);
     ProcedureTestingUtility.assertProcNotFailed(procExec, procId);
 
-    assertTrue(UTIL.getHBaseCluster().getRegions(tableName).size() == 2, "not able to split table");
+    assertEquals(2, UTIL.getHBaseCluster().getRegions(tableName).size(), "not able to split table");
 
     // disable table
     UTIL.getAdmin().disableTable(tableName);
@@ -155,6 +156,57 @@ public void testSplitTableRegion() throws Exception {
       regionInfoMap.get(tableRegions.get(1).getRegionInfo()));
   }
 
+  @Test
+  public void testRITWithSplitTableRegion() throws Exception {
+    final TableName tableName = TableName.valueOf(testMethodName);
+    final ProcedureExecutor<MasterProcedureEnv> procExec = getMasterProcedureExecutor();
+
+    RegionInfo[] regions =
+      MasterProcedureTestingUtility.createTable(procExec, tableName, null, columnFamilyName);
+    insertData(UTIL, tableName, rowCount, startRowNum, columnFamilyName);
+    int splitRowNum = startRowNum + rowCount / 2;
+    byte[] splitKey = Bytes.toBytes("" + splitRowNum);
+
+    assertNotNull(regions, "not able to find a splittable region");
+    assertEquals(1, regions.length, "not able to find a splittable region");
+    assertFalse(AssignmentTestingUtil.isRegionInTransition(regions[0],
+      UTIL.getHBaseCluster().getMaster().getAssignmentManager()));
+
+    ServerName targetRS = UTIL.getHBaseCluster().getMaster().getAssignmentManager()
+      .getRegionStates().getRegionServerOfRegion(regions[0]);
+    // Split region of the table
+    long procId = procExec.submitProcedure(
+      new SplitTableRegionProcedure(procExec.getEnvironment(), regions[0], splitKey));
+    // Wait the completion
+    ProcedureTestingUtility.waitProcedure(procExec, procId);
+    ProcedureTestingUtility.assertProcNotFailed(procExec, procId);
+
+    assertEquals(2, UTIL.getHBaseCluster().getRegions(tableName).size(), "not able to split table");
+    assertFalse(AssignmentTestingUtil.isRegionInTransition(regions[0],
+      UTIL.getHBaseCluster().getMaster().getAssignmentManager()));
+    // As there are only 3 RS, start one more RS before expiring one
+    UTIL.getHBaseCluster().startRegionServer();
+
+    // We don't want SCP to complete so kill PR it after store update
+    ProcedureTestingUtility
+      .toggleKillAfterStoreUpdate(UTIL.getHBaseCluster().getMaster().getMasterProcedureExecutor());
+    // stop RS holding split parent to create SCP and add RS into deadServerList
+    UTIL.getHBaseCluster().getMaster().getServerManager().expireServer(targetRS);
+
+    // stop master
+    UTIL.getHBaseCluster().stopMaster(0);
+    UTIL.getHBaseCluster().waitOnMaster(0);
+
+    // restart master
+    UTIL.getHBaseCluster().startMaster();
+    assertTrue(UTIL.getHBaseCluster().waitForActiveAndReadyMaster(30000),
+      "Master failed to initialize in in 30 seconds");
+    UTIL.invalidateConnection();
+
+    assertFalse(AssignmentTestingUtil.isRegionInTransition(regions[0],
+      UTIL.getHBaseCluster().getMaster().getAssignmentManager()));
+  }
+
   @Test
   public void testSplitStoreFiles() throws Exception {
     final TableName tableName = TableName.valueOf(testMethodName);

hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestSplitTransactionOnCluster.java

@@ -907,7 +907,8 @@ public void testSplitRegionWithNoStoreFiles() throws Exception {
       } catch (DoNotRetryIOException e) {
         // Expected
       }
-      assertFalse(am.isRegionInTransition(hri), "Split region can't be assigned");
+      assertFalse(AssignmentTestingUtil.isRegionInTransition(hri, am),
+        "Split region can't be assigned");
       assertTrue(regionStates.isRegionInState(hri, State.SPLIT));
 
       // We should not be able to unassign it either
@@ -917,7 +918,8 @@ public void testSplitRegionWithNoStoreFiles() throws Exception {
       } catch (DoNotRetryIOException e) {
         // Expected
       }
-      assertFalse(am.isRegionInTransition(hri), "Split region can't be unassigned");
+      assertFalse(AssignmentTestingUtil.isRegionInTransition(hri, am),
+        "Split region can't be unassigned");
       assertTrue(regionStates.isRegionInState(hri, State.SPLIT));
     } finally {
       admin.balancerSwitch(true, false);